T1 mapping provides quantitative information on tissue alterations and gadolinium kinetics. In the heart, the ability to identify myocardial edema and the potential to identify diffuse interstitial fibrosis are of particular interest.
Mapping of T1 relaxation times typically requires the acquisition of multiple images with different inversion times in order to allow for an accurate fitting of the underlying T1 curve. Dedicated cardiac T1 mapping schemes typically acquire a sufficient number of images within one breath-hold. Dedicated ECG (electrocardiogram)-triggered Look-Locker Inversion Recovery (IR) techniques have already been described for cardiac magnetic resonance (MR) imaging, see e.g. Messroghli et al., “Modified Look-Locker Inversion recovery (MOLLI) for High-Resolution T1 Mapping of the Heart”, Magn. Reson. Med. (2004), 52: 141-146; and Messroghli et al., “Human Myocardium: Single-Breath-hold MR T1 Mapping with High Spatial Resolution—Reproducibility Study”, Radiology (2006), 238: 1004-1012. However, such techniques use non-segmented acquisitions with durations of approximately 150 to 200 ms for each raw image. While it could be shown that this acquisition duration is adequate to acquire images at end-diastole for heart rates up to 100 beats per minute (bpm) with high reproducibility, this approach is not suitable for use in small animals where heart rates in the range of 200 to 600 bpm are to be expected. Consequently, alternative approaches are warranted for these situations, which usually lead to a significant rise in over-all acquisition time. This might not be desirable for imaging protocols where other types of MR images are to be collected within the same session, causing long scan times that might potentially exceed the limits where the animals can be studied safely under stable conditions.